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Appendix
Reference information is provided in the appendix.
EDITFEKO Cards
Each geometry and calculation request are entered on a separate line in the .pre and are referred to as cards.
Control Cards
Control cards are used to specify requests and solver settings and are placed after the EG card in the .pre file.
SK Card
This card defines a skin effect, ohmic losses, dielectric sheet, characterised surface definition, arbitrary user defined impedance boundary condition on wire segments and surface elements or a dielectric surface impedance approximation. Layered dielectrics can also be defined.
Dielectric Surface Impedance Approximation
This option allows a dielectric region to be solved with the dielectric surface impedance approximation.

Welcome
Release Notes
See what's new in the latest release.
Get Started
The Feko Getting Started Guide contains step-by-step instructions on how to get started with Feko.
Examples
The Feko Example Guide contains a collection of examples that teaches you Feko concepts and essentials.
Introduction to Feko
Feko is a comprehensive electromagnetic solver with multiple solution methods that is used for electromagnetic field analyses involving 3D objects of arbitrary shapes.
CADFEKO
CADFEKO is used to create and mesh the geometry or model mesh, specify the solution settings and calculation requests in a graphical environment.
POSTFEKO
POSTFEKO, the Feko post processor, is used to display the model (configuration and mesh), results on graphs and 3D views.
EDITFEKO
EDITFEKO is used to construct advanced models (both the geometry and solution requirements) using a high-level scripting language which includes loops and conditional statements.
Feko Solution Methods
One of the key features in Feko is that it includes a broad set of unique and hybridised solution methods. Effective use of Feko features requires an understanding of the available methods.
Optimisation in Feko
Feko offers state-of-the-art optimisation engines based on generic algorithm (GA) and other methods, which can be used to automatically optimise the design and determine the optimum solution.
Feko Utilities
The Feko utilities consist of PREFEKO, OPTFEKO, ADAPTFEKO, the Launcher utility, Updater and the crash reporter.
Description of the Output File of Feko
Feko writes all the results to an ASCII output file .out as well as a binary output file .bof for usage by POSTFEKO. Use the .out file to obtain additional information about the solution.
Feko Application Macros
A large collection of application macros are available for CADFEKO and POSTFEKO.
Scripts and Application Programming Interface (API)
CADFEKO and POSTFEKO have a powerful, fast, lightweight scripting language integrated into the application allowing you to create models, get hold of simulation results and model configuration information as well as manipulation of data and automate repetitive tasks.
Appendix
Reference information is provided in the appendix.
- Application Programming Interface (API)
  CADFEKO and POSTFEKO have a powerful, fast, lightweight scripting language integrated into the application that allows you to create models, get hold of simulation results and model configuration information and much more.
- EDITFEKO Cards
  Each geometry and calculation request are entered on a separate line in the .pre and are referred to as cards.
  - Geometry Cards
    Geometry cards are used to create geometry and are placed before the EG card in the .pre file.
  - Control Cards
    Control cards are used to specify requests and solver settings and are placed after the EG card in the .pre file.
    - AX Cards
      These cards define the type of excitation (source) as well as other relevant parameters.
    - A0 Card
      The A0 card defines a linearly polarised incident plane wave.
    - A1 Card
      This card defines a voltage source that is placed on a wire segment.
    - A2 Card
      With this card a voltage source is placed at a node between two segments or between a segment and a triangle, ground plane or polygonal plate. It is mostly used to feed wires attached to plates.
    - A3 Card
      This card realises excitation by a magnetic ring current (TEM-frill) on a segment. It gives an an accurate model of a coaxial feed, but requires both the inner and outer radii.
    - A5 Card
      This card specifies excitation by an electric Hertzian dipole
    - A6 Card
      This card specifies excitation by an elementary magnetic Hertzian dipole.
    - A7 Card
      This card specifies a voltage source on an edge between two triangles or at a connection between a single triangle and a PEC ground plane or UTD plate.
    - AB Card
      This card is used to create a FEM modal excitation, which is the fundamental mode of the associated, infinitely long guided wave structure of the modal port.
    - AC Card
      This card inputs data from a .rsd file containing the geometry of a transmission line or PCB structure and the current distribution along this line or on the PCB for one or more frequencies.
    - AE Card
      This card specifies an excitation at an edge between triangular surface elements.
    - AF Card
      This card defines a uniform electric current filament impressed between two arbitrary points inside of the FEM region (it does not have to coincide with the edges of tetrahedra). This can be used to excite for instance a patch antenna.
    - AI Card
      This card defines an impressed current source that varies linearly between the values at the start and end points.
    - AJ Card
      This card uses current data calculated for a PCB as an impressed current source. The data is read from an Altair PollEx .rei file.
    - AK Card
      This card defines a voltage source to a radiating cable with or without irradiation considered.
    - AM Card
      This card uses model solution coefficients to define an impressed current source. The model solution coefficients are imported from a .sol file.
    - AN Card
      This card defines a voltage source that can be added to any port of a general non-radiating network and that does not have a connection to geometry.
    - AP Card
      This card defines a planar, cylindrical or spherical aperture of measured or calculated field values that is converted by PREFEKO internally into an equivalent array of electric and magnetic dipoles (A5/A6 cards).
    - AR Card
      This card uses the radiation pattern of an antenna as an impressed source. The data is read from file or defined in the .pre file.
    - AS Card
      The AS card defines an excitation by means of impressed spherical modes which are either radiating (propagating in positive r direction to infinity, with r being the radius in a spherical coordinate system) or incident onto a structure (propagating towards the origin r = 0).
    - AT Card
      This card defines a voltage source that is applied to a voxel mesh in connection with a finite difference time domain (FDTD) method.
    - AV Card
      This card defines an impressed current source similar to the AI card but that makes electrical contact with a conducting surface.
    - AW Card
      The AW card is a two line card which is used to define a waveguide port excitation. With this card a waveguide port excitation by an impressed mode on a rectangular, circular, or coaxial waveguide, can be modelled or the impressed travelling modes in all waveguides of a multi-port network can be imported from a .fim file.
    - BO Card
      This card defines a ground plane with the reflection coefficient approximation. All computations that follow this card will include the ground plane (except when it is applied to solution requests where its is only considered in post-processing calculations).
    - CA Card
      The CA card is used to define a section of a shielded cable which is used for irradiation (for example, computing induced currents and voltages at the cable terminals) due to external sources. Transmission line theory is applied, for example, no need to discretise the cable as with the MoM. A section is defined as a straight part of a cable (one cable can consist of multiple sections).
    - CD Card
      This card defines a cable cross section.
    - CF Card
      This card sets the type of integral equation for perfectly conducting metallic surfaces.
    - CG Card
      The CG card defines the method to solve the matrix equation.
    - CH Card
      This card is used to group cable harness specific properties.
    - CI Card
      The CI card is used to define interconnections and terminations between cables.
    - CM Card
      The CM card is used to couple Feko with the transmission line simulation programs CableMod or CRIPTE or the PCB tool PCBMod to calculate the coupling of electromagnetic fields into transmission lines. (The AC card is used for the case of radiation by these lines.)
    - CO Card
      This card specifies a dielectric or magnetic coating of wire segments or triangular surface elements.
    - CR Card
      This card specifies the orientation of a 3D anisotropic medium.
    - CS Card
      This card defines a cable path as well as the centre or reference location to which a cable cross section definition is applied.
    - DA Card
      This card controls the export of data to additional ASCII files. For example the currents can be exported to the .out file or S-parameters can be exported to a Touchstone file.
    - DI Card
      This card can be used to define the frequency dependent or independent material characteristics of a dielectric medium, metallic medium or an impedance sheet.
    - DL Card
      This card is used to define an isotropic or anisotropic layered medium by specifying the label of the material to be used for each layer.
    - EE Card
      The EE card requests an a-posteriori error indicator whereby Feko can test the solution against an unconstrained physical test. The result is to give an indication of the region where local mesh refinement should be considered.
    - EN Card
      The EN card indicates the end of the input file. It is essential and has no parameters.
    - FD Card
      This card sets the solver settings for the finite difference time domain (FDTD) solver.
    - FE Card
      This card controls the calculation of near fields.
    - FF Card
      This card controls the calculation of the far fields in spherical or Cartesian coordinates.
    - FR Card
      The FR card sets the frequency/frequencies (in Hz), at which the solution will be obtained.
    - GF Card
      This card includes the complexities of dielectric environments using special Green's functions. The Green's functions relates the fields in space to the sources.
    - KC Card
      The KC card facilitates the transferral of connector names from CADFEKO to POSTFEKO.
    - KS Card
      The KS card facilitates the transferral of signal names from CADFEKO to POSTFEKO.
    - L2 Card
      This L2 card places a load (complex impedance) on a node.
    - LC Card
      The LC card specifies complex, series and parallel circuits applied between connector pins and also between a connector pin and ground.
    - LD Card
      This card specifies a distributed resistive, capacitive or inductive loading or a series combination of these loads for a segment(s).
    - LE Card
      This card specifies complex series and parallel circuits applied to an edge between surface triangles.
    - LF Card
      This card impresses a complex impedance between two points inside a FEM mesh.
    - LN Card
      This card defines a complex load to any non-radiating network port.
    - LP Card
      This card assigns a parallel circuit of discrete elements to a segment.
    - LS Card
      This card assigns a series circuit of discrete elements in series to a segment.
    - LT Card
      This card assigns a resistor, inductor or capacitor in series to a voxel mesh for the finite difference time domain (FDTD) method.
    - LZ Card
      This card can be used to assign a complex impedance to a segment.
    - MD Card
      This card exports the model and solution coefficients to a .sol file.
    - NW Card
      This card defines a linear non-radiating network.
    - OF Card
      This card specifies an offset for the origin of the coordinate system for near and far field calculations. It also facilitates using only a part of the structure through label selection when calculating fields.
    - OM Card
      This card can be used to calculate the weighted set of orthogonal current-modes which are supported on a conducting surface.
    - OS Card
      With this card the currents on the surfaces and the segments can be extracted.
    - PP Card
      This card defines the phase shift of the excitation between one unit cell and the next for periodic boundary conditions. The unit cell for a PBC calculation is specified with the PE card.
    - PR Card
      This card defines a voltage or current probe along a cable.
    - PS Card
      This card is for general program control such as storing the currents for re-use in a subsequent version of the model in order to save runtime.
    - PW Card
      The PW card specifies the radiated power or the source power. It can also be used to consider mismatch.
    - RA Card
      This card defines an ideal receiving antenna that can be placed anywhere in the model.
    - SA Card
      This card controls calculations of the specific absorption rate (SAR) in a dielectric.
    - SB Card
      This card specifies an external magnetostatic bias field applied to a 3D anisotropic medium (ferrite).
    - SC Card
      This card defines a SPICE circuit that can be used when defining a load.
    - SD Card
      This card defines the impedance or admittance of an individual cable shield layer. The shield layers are used when defining a cable shield (SH card).
    - SH Card
      This card defines a cable shield consisting either of a single layer or two layers.
    - SK Card
      This card defines a skin effect, ohmic losses, dielectric sheet, characterised surface definition, arbitrary user defined impedance boundary condition on wire segments and surface elements or a dielectric surface impedance approximation. Layered dielectrics can also be defined.
      - Skin Effect and Ohmic Losses
        Specify the skin effect using either the exact expression, high frequency approximation or static approximation (Ohmic losses).
      - Triangles as Thin Isotropic Dielectric Sheet
        This option defines a thin isotropic dielectric sheet (may consist of several layers).
      - Triangles as Thin Anisotropic Dielectric Sheet
        This option defines a thin anisotropic dielectric sheet. The definition is similar to the isotropic dielectric sheet, except that the layers are anisotropic.
      - Triangles Using a Characterised Surface Definition
        This option defines a characterised surface.
      - User Defined Surface Impedance
        This option allows the definition of a complex user defined surface impedance, Z_s.
      - Dielectric Surface Impedance Approximation
        This option allows a dielectric region to be solved with the dielectric surface impedance approximation.
    - SP Card
      This card defines an S-parameter (S-matrix) request for active sources.
    - TL Card
      This card connects a non-radiating transmission line between Feko geometry or other general non-radiating networks or transmission lines.
    - TR Card
      This card is used to calculate the transmission and reflection coefficients for a plane wave interacting with a planar structure.
    - WD Card
      This card is used to define the dielectric properties of each of the windscreen glass layers. These layers are placed over the antenna elements by defining the relative position of the top layer to the reference plane.
- How-Tos
  A collection of how-tos are included that covers advanced concepts.
- FAQ
  A collection of frequently asked questions (FAQ) relating to advanced concepts are included.
- Troubleshooting
  Common problems that you may encounter are discussed as well as their solutions.
- Meshing
  When meshing a model, you can either use the automatic meshing algorithm to calculate the appropriate mesh settings or you can specify the mesh sizes. When you specify the mesh sizes, the mesh sizes should adhere to certain guidelines.
- SAR Standards
  Feko makes use of a local peak SAR algorithm.
- Solution Control
  Control the execution of Feko by specifying the memory management and environment variables.
- Read MAT, LUD, RHS and STR Files
  The .mat file, .lud file and .rhs file are not generated by default, but can be read externally.
- Integration With Other Tools
  Feko integrates with various products within Altair HyperWorks Products such as HyperStudy. Integration with third-party products is also supported through the powerful scripting and plug-in infrastructure.
- SPICE3f5
  Use the correct structure, convention and syntax for a SPICE circuit definition in Feko.
- List of Acronyms and Abbreviations
  View the list of commonly used acronyms in Feko.
- Summary of Files
  Feko creates and uses many different file types. It is useful to know what is stored in the various files and weather they were created by Feko and if it is safe to delete them. The files are grouped as either native files that have been created by Feko or non-native files that are supported by Feko. Non-native files are often exported by Feko even if the formats are not under the control of the Feko development team.
- Common Errors and Warnings
  A Feko Errors, Warnings and Notes Reference Guide is available as a reference for messages that may be encountered in Feko.

Dielectric Surface Impedance Approximation

This option allows a dielectric region to be solved with the dielectric surface impedance approximation.

Figure 1. The SK - Add a skin effect (finite conductivity) dialog.

Note: The surface impedance is calculated from the material properties defined at the DI card.

Parameters:

Material label: Label of the material (as specified in the DI card) which will be used for the calculation of the dielectric surface impedance.

The following dielectric surface impedance expression will be used:

Z_{s} = \sqrt{\frac{μ_{0}}{ϵ_{0} ε_{r} - j \frac{σ}{ω}}}

where the relative permittivity

ε_{r}

and conductivity

σ

are defined at a specific angular frequency

ω = 2 π f